Electromagnet



R. R. DUNLOP ELECTROMAGET Filed Jan. 26, 1924 MR, DM

Mer/f Dep. 1o, 1929.v

ik ma Patented Dec. `10, 1929y i "'UNITED STA-TES PATENT? OFI-ics ROBERTABOWSE DUNLOIhAOF COLUMBUS, OHIO, `ASSIGNOIR. TO THE lil'lilFI'IEtIlY MANU- l VFACTHIRING' COMPANY, OF COLUMBUS, OHIO, A CORPORATION OF OHIO ELECTROMAGNET i Application filed January 26, 1924. Serial No. 688,854. K

The present invention relatesto certain new and useful improvements inrelectromagnets and method of makingsame, and particularly to that class of electromagnets which is adapt- 5 ed to extend parallel `to the cylinder of an electric controller in rclose `proximity to the contact fingers to `extinguish the arcs forming at the points of contact between said ngersand the cylinder. l

0 4As heretofore constructed, electromagnets of the class referred to have been formedr by winding a wire of suitablecross section upon a mandrel to form a helical conductor having the desired magnetic characteristics, the ends `:i of which4 were adaptedto be clamped or soldered into suitable connecting devicesk associated with the apparatus of which the magnet forms a part. Such acoil is more or'less' distorted byl removal from Vthe mandrel, and

:0 the character of its terminal connections reny ders its formfstill more irregular, materially increasing the vdifliculty of assembling the apparatus.

It is the especial object of this invention to provide an electromagnetof improvedV construction and a method of producing such magnetas to insure uniformity of dimensions, combined with economy of manufacture and convenience ofinstallation. A

The device yand the method by which I attain. these objectsis fully set forth in the following specification and illustrated in the y accompanying drawings, of which- Fig. 1 is an elevation of the preferred embodiment of my invention, the insulating shield being partially broken away to reveal theiconstruction of the .conductor coil. i

Fig. 2 is a sectional viewy taken along the longitudinal central. planeof the device illustrated in Fig. 1. Y A

Likenumerals refer to similar parts in the several figures, f; y

As illustrated inthe drawings,` my improved.` electromagnet comprises' a metallic tube 1, preferably a copper tube, through the wall of which is cut a slot 2, preferably disposed in spiral form, to form a helical conductor adapted to generate A,a magnetic field when an electriccurrent flows through such conductor from one endlof the tube tothe other. The slotl 2 preferablyterminates .nearY the ends of the tube, thereby forming a closed ring 3 at each end of the coil, and into these rings proj ect the lugs 4, preferably cylindrical and preferably formed integral withthe supporting brackets 5. The lugs 4 are split longitudinally and are litted with expansionmembers, here shown as screws 6, of such shape and proportion that when said membersk are.v

driven inwardly, said lugs will be expanded into forced engagement with the walls of the rings 3 to secure the magnet coil yto the supporting brackets and insure` good electrical connections between thesel parts.

It will be noted that a threaded bore is i provided in each supporting member and its associated split lug 4 and terminates in a tapered portion adapted to vcooperate with the tapered end of the screw to cause expansion of the split lugs when the screws are driven home. f l y In service, the supporting bracketsV 5 are connected with the circuits of theap'paratus of which this magnet'forms a part, and the flow of electric current from one supporting bracket to the other through the conductor 1 generates the desired magnetic field in the manner which is Well understood in the art, Asuitable iron core 7 is positioned inside the coil 1 to concentrate the magnetic field, and a suitable insulating cylinder 8 -of suitable material, preferably a noncombustible insulating material, surroundsthe core 7 to elec-` l' trically separate it from the conductorv 1.

Suitable insulating disks 9 are provided at each end ofthe core 7 to prevent its electr-ical connection with the supporting lugs 4, and a4 cylindrical shield l0 of any suitablematerial, preferably a non-combustible insulating material, protectsv the magnet from external short circuit. Y Y y By the construction above described, and following my method, eXtreme accuracyfboth of form and dimensions, is secured,permitl ting the convenient use. in assembling the;

Such mechanical changes and the adoption of equivalent mechanical expedients for those herein illustrated as involve only mechanical skill may be made and still be within the range of my invention.

I claim 1. In an electromagnet, the combination of a helical conductor, and a support therefor having an expansible device projecting into the end of said conductor, and means for expanding said device.

2. In an electromagnet, the combination of a helical conductor, a support having an integral expansible plug fitting within an end of said helical conductor, a screwcarried by said support for expanding said plug, and a nut carried by said screw and abutting said support.

3. In an electro-magnet the combination of a metallic tube having a spiral slot formed in its wall throughout its major middle portion and terminating short ofthe ends thereof to provide unslotted end portions, expansible supporting devices projecting into the unslotted ends of said tube, and means for expanding these devices in the unslotted ends.

' 4. In an electro-magnet the combination of a metallic tube having` a spiral slot formed in its wall throughout its major middle portion and terminating short ofthe ends thereof to provide unslotted end portions, a plurality of segments forming an annular plug in the unslotted ends of said tube, and means for expanding said segments to grip said unslotted ends interiorly.

5. In an electro-magnet the combination of a metallic tube having a spiral slot formed in its wall throughout its major middle portion and terminating short of the ends thereof to provide unslotted end portions, a plurality of threaded segments forming an annular plug in the unslotted ends of said tube, and a screw having a wedge-shaped portion engaging said plug members to expand the same and grip the unslotted ends ot' the tube interiorly. Y

6. In an electro-magnet the combination of a metallic tube having a spiral slot formed in its wall throughout its major middle portion and terminating short of the ends thereof to provide unslotted end portions, a plurality of threaded segments forming an annular plug in the unslotted ends of said tube, a screw having a wedge-shaped portion engaging said plug members to expand the same and grip the unslotted ends of the tube interiorly, and supports formed integral with said plug members.

7 In an electromagnet, the combination of a helical conductor, a tubular insulating member surrounding said conductor and being coextensive therewith, and supports frictionally engaging within the ends of said conductor' and abutting the ends of said insulating member.

8. In an electromagnet, the combination with a helical conductor, a tubular insulating member mounted upon said conductor and being coextensive therewith, a support for each end of the magnet having an expansible device rojecting into its respective end of said conc uctor, and said supports being arranged to abut the ends of said tubular insulating member.

9. An electro-magnet 'coil comprising a helical conductor, supportingl means extending axially thereof and into the ends of the same for establishing electrical connection therewith, and a tubular insulating member surrounding said conductor and having its ends abutting the supporting means to retain said member in position.

10. An electro-magnet coil comprising a helical conductor, supporting devices extending axially thereof and into theends of said conductor for establishing electrical connection therewith, a core for the conductor, and insulating devices arranged between the ends of the core and said supporting devices.

11. An electro-magnet coil comprising a helical conductor, supporting devices extending co-axially thereof and into opposite ends of said conductor for establishing electrical connection therewith, a core for the conductor, an insulating sleeve receiving said core to space the same from the conductor, and insulating discs arranged between the ends of said sleeve and said supporting devices.

12. In an electro-magnet, a helical conductor, and a support therefor having split cylindrical lugs projecting into the end of said conductor, split lugs.

13. In an electromagnet, the combination of a helical conductor, a support therefor having a split cylindrical lug projecting into the end of said conductor, said lug having a threaded bore and tapered portion, and a screw mounted in said bore and having a tapered endto cooperate with the tapered portionof said lug for expanding the same.

14:. An electromagnet coil comprising a tubular helical conductor, supporting members extending co-axiallyjthereof and into the ends of vsaid conductor for establishing electrical connection therewith, and a tubular insulating member surrounding said conductor and having its ends abutting said supporting members to retain said insulating member in position.

15. An electrical device comprising a helical conductor, Vand combined supporting and conductor means extending axially thereof and into the end of the same for supporting and making an electrical contact with said conductor.l

16. An electrical device comprising a metal tube having a spiral slot formed in its wall throughout its4 majorl middle portion and and means forexpanding said terminating short of the ends thereof to pro- 

